After confirming his/her qualification for 72/144-hour visa-free transit, the immigration inspection station will issue the foreign passenger a temporary entry permit. Then from 00:00 of the next day upon his/her arrival in China, he/she can stay in the designated areas without a Chinese visa for 72/144 hours.
more policy on https://3btaxi.com/index.php/144hourstwovlayover.html